Kingdom Hearts: Hearts of Chaos
by Samsapoping
Summary: During the night of meteor shower, the Destiny Trio find a blue hedgehog and a mystical diamond washed up on their home. The trio offer to help him find his friends, but upon taking him to Radiant Gardens, Kairi becomes the key to an evil doctor's scheme in conquering the universe. Set after KH3 and whatever the next KH game will be. Sokai, SonAmy
1. Chapter 1: Meteor Control

**This was originally going to be a Marvel X KH fanfic, but then I decided to change it into a Sonic crosover instead.**

**Enjoy!**

* * *

_**SPOILERS: This story is set AFTER KH3! Finish the game or READ AT YOUR OWN RISK!**_

* * *

**Destiny Islands**

Sora's POV

It was a peaceful night on the islands as my friends and I were simply enjoying the warm breeze. The sky was beautifully covered with hundreds of stars shining down at us. And each star represented a world shining like a beacon while we were all relaxing by a large palm tree.

"Mmm…"

Fortunately, one of my best friends was resting on my lap, giving me something even more beautiful to gaze upon. All the stars in the night sky were nothing compared to the auburn haired princess who was dreaming peacefully on me. A Princess of Heart who became my girlfriend, but more importantly, a princess who I vowed to protect forever. She was my light and ever since I came back from Shibuya, I felt like I owed her something even bigger than life.

"Sora." My other best friend called out.

"Huh?" I muttered.

I quickly glanced back up at the sky, only to find a fading shooting star soaring away.

"Too late." I heard my friend commented.

The one who was really enjoying the meteor shower was a silver haired boy named, Riku. My closest friend who felt more like a brother to me and a Keyblade Master who went through even more trouble than me during our adventures. The two of us had both experienced hurt and suffering deep within our hearts multiple times, but we managed to come back around.

But upon getting possessed, falling into the deepest sleep, or even sacrificing yourself TWICE to save your love ones, I still felt like the one who suffered the most was the girl who was sleeping with a smile on her face.

"You know, Sora…"

"Tonight is like the night Kairi first arrived to the islands." Riku exclaimed.

I simply nodded at Riku and slowly looked down at the sleeping princess, remembering that night. She was washed up onto the islands back when Riku and I were little and was living at the Mayor's House. Ever since Riku and I first met her, our lives became extraordinary. She was the main reason why we wanted to see other worlds and it led us to saving them multiple times.

But upon remembering our lives, I began having a lot of symphony towards Kairi. The more I remembered how much she suffered throughout her life, the more pain my heart received. She lost her Grandmother upon arriving to the islands that night, got her heart taken by the Heartless when we first got separated, waited for Riku and I to return home for a long time, but then got kidnapped by the original Organization XIII.

As if those weren't bad enough for her, she met a terrible fate caused by Master Xehanort. A fate which resulted the old Keyblade Master in killing the princess with one single strike, shattering her spirit into a million pieces. I managed to save her by using the Power of Waking, but it cost me my own life, separating us once again. If it wasn't for Riku helping me get back home, I would've never seen her or any of my friends again.

"Sora!"

My train of thoughts stopped in an instant a I heard Riku calling my name. I looked away from Kairi again and saw my best friend pointing at the sky in a confusing manner. My head rose up, only to find something green falling from the sky.

"A green shooting star?" I blinked.

"I don't think that's a shooting star." Riku guessed.

"A green comet?" I wondered.

"Whatever it is, it's going to fall into the sea pretty soon." The keyblade master answered back.

Upon gazing at whatever the green thing, I thought it just going to be some random space rock. Then suddenly, I got a strange vision; which gave me a closer look at what was coming.

"Huh?!" I gasped.

What was heading down to the islands was something completely unusual. Through the green light, was some kind of blue anthropomorphic creature. A blue hedgehog looking with white gloves and red and white striped shoes. Whatever was glowing green seemed as if it was glowing from in its right hand.

"Sora?" Riku spoke in a concerning voice.

"A blue hedgehog?" I said with my eyes widely opened.

"What?!" The Keyblade Master responded.

"I just saw some kind of blue hedgehog falling to the sea." I clarified.

We then gazed back to the sky as the strange glowing creature descending into the ocean. It fell into the water, illuminating the sea and blinding us in the process.

"I'll go rescue it!" Riku decided.

"Sora, stay with Kairi." He ordered.

"As if she wasn't sleeping on me." I stated the obvious.

The Keyblade Master ran off into the ocean, leaving me with the sleeping Princess of Heart. Fortunately, the princess began waking up as she slowly lifted herself off of my lap, rubbing the sleep off of her eyelids.

"Is...is something going on?" Kairi groaned, waking up.

"Where's Riku?" She asked.

"Oh, he's... taking a quick swim." I quickly answered.

"Huh?" The princess muttered.

It was the closest thing I could say towards the truth. The last thing I wanted to do was to make Kairi become worried upon saying how an unconscious animal fell into the sea. Riku was strong enough to save the animal and it wasn't a big deal to cry about it. Unfortunately, we still had to deal with the intense green light.

"What in the…" Kairi reacted, covering her eyes a bit.

Thankfully, the light stopped instantly, but what happened next surprised us. In a blink of an eye, Riku appeared with the blue animal, collapsing to the sand with heavy breaths.

"Huh?" Riku muttered.

"Riku!" Kairi and I cried.

We ran over to our best friend in concern as he was kneeling in disbelief, wondering what happened. Kairi went over to the unconscious animal while I went to check on Riku.

"Riku, are you okay?" I asked, offering to help him.

"Yeah." Riku nodded.

"But how did we get back so quick?" He wondered.

"What happened?" Kairi asked.

"Sora and I found him falling into the ocean, but when I dove in to grab him, he and I were engulfed by a green light." The keyblade master explained.

"Green light?" Kairi and I muttered.

I then glanced over to the unconscious animal and got a better view on him. Only time, I had an obvious guess of what was illuminating the scenery as I found a sparkling object rolling out of the animal's left glove. A small emerald colored diamond that was sparkling like a star.

"Green light…" Kairi whispered.

The Princess of Heart crouched towards the diamond and pick it up, getting a better examination of it. Like gazing at someone's heart, she and I ending up staring at the green diamond in awe.

"I can feel something." Kairi mentioned.

"Kairi?" I blinked.

"I can feel some kind of power from within this diamond." The princess clarified.

"Huh?" I muttered.

"That probably explains how he and I got here." Riku figured.

After seeing a plethora of mystical items throughout my adventures, Riku's words became a good possibility. Upon staring at the diamond with Kairi, I too began to feel some strange energy coming from it. Some kind of light energy calling to the princess and I.

"What's strange is that I can sense it being some kind of light energy." I exclaimed, placing my hand over Kairi's.

"Light energy?" Riku wondered.

Suddenly, the diamond started to reacting to our touches. A bright light light illuminated at us, swallowing all of us with its glow. Overwhelmed by our situation, I tightened my grip on the diamond and Kairi's hand, trying to shield her from whatever was coming for us. Extraordinary powers were flowing through me, striking my heart hard in attempt for me to let go. However, what really struck me was hearing the princess grunting in pain.

"Just hang in there, Kairi!" I called to the princess.

"S-sora!" She grunted.

Before we knew it, the light faded as we all fell back onto the beach. Unfortunately, we were at the wrong side of it as I immediately recognized where we got warped to. Of all the worlds I've been to, it was the last place to see with Kairi.

* * *

_**Please Review and Comment!**_


	2. Chapter 2: Princess of Chaos

**Enjoy!**

* * *

"Is everyone okay?" I asked.

"Y-yes." The Princess of Heart spoke.

"We're okay, Sora." Riku answered.

"Then, we better put our guards up." I suggested.

"Why? What's wrong?" Kairi wondered.

"Because we got sent to the Realm of Darkness." I mentioned.

"Huh?!" The Keyblade Master gasped.

Upon seeing the gloomy beach with the white sun at us, a slight ounce of fear began to consume me as I remembered the dangers Riku and I fought during our last visit. It was on the same beach where we fought and rescued Aqua, but it was also where Riku and The King were struggling against the Heartless. A fear that I didn't want to face against because Kairi was with us. The princess was still an inexperienced keyblade wielder and she was now in the realm where she was easy prey to the Heartless.

"Kairi, stay with Sora!" Riku ordered.

"Huh?" The Princess of Heart muttered.

"The Heartless in this realm are even stronger than the ones we fought in the Realm of Light." The Keyblade Master warned us.

Just then, I could sense the worries Kairi started to have. Worries I didn't want her to have. I could sense her heart not worrying about our safety, but our unexpected guest we also brought. Even though we all had to guard the still unconscious blue hedgehog creature, I showed Kairi that protecting her was my biggest priority.

"Don't worry, I'll keep you safe!" I tried to cheer the princess up.

"We just have to open the Door to the Light and we'll be back home." I explained.

"It's not that what concerns me." She responded.

"Huh?" I muttered.

"It's this diamond we're holding." She clarified.

"I've never felt light magic like that before." She explained.

I then took another glance at the green diamond, releasing my grip off of it. The mystical treasure was still glowing brightly in Kairi's hands, but our arrival to the Realm of Darkness may have proven Riku's hypothesis. The diamond's magic must have warped us to our current location, but the real question now was, "Why?". Why did it send us to the Realm of Darkness?

"Now I know I'm still getting to know my power, but this diamond seems to contain some powerful magic that I'm totally unaware of." Kairi said.

"Makes me wonder how he got his hands on it." I replied, pointing at his hands at the hedgehog.

Unfortunately, our trains of thoughts and our checkings on the hedgehog quickly halted as we saw that we're getting even more company. A group of Shadows began emerging from the sand, surrounding us as an ambush as we summoned our keyblades. Although, they became the least of our worries as we watched them combine into somewhere far more dangerous. A spinning Demon Tower made up of hundreds of Shadows.

"Kairi, stay back with the blue hedgehog and take out any Heartless that come near you two!" Riku shouted.

"Got it!" The princess nodded, holding her keyblade.

"Sora?" The Keyblade Master called out.

"I'm right with you, Riku!" I spoke back, running beside my best friend.

"Be careful, Kairi!" I turned my head back at my girlfriend.

"I will!" She nodded again.

* * *

Kairi's POV

And with that, I had my guard up while my two best friends went all out with the Heartless. Despite me fighting the easier fights, I could see what the boys wanted me to do. The more they whaled on them, the more Heartless came flying out of it. Flying out for me to take out with my keyblade whenever they came near me.

"Stay back!" I shouted, whacking my keyblade at a Shadow.

"Look out!

With much strength, I swung my weapon three to four times until it exploded into a heart. Then, I repeated the assault on another foe. Each Shadow I slayed became a floating heart that faded away. Fortunately, I had the easy task while Sora and Riku were doing all the hard work.

Upon protecting the unconscious hedgehog, I was watching the boys striking the merged Heartless with everything they had. Through their constant slashes, the foe slivered around like a worm, trying to whack them like a giant worm. It even split back into dozens of tiny Shadows, surrounding us with their yellow eyes staring at our hearts.

"KAIRI, LOOK OUT!" Sora cried.

Unfortunately, the Heartless' new target was me as they began turning orange, beginning to charge at me and the blue critter. Overwhelmed by the sheer numbers of foes, I quickly covered the animal and closed my eyes, awaiting for my unfortunate devourment.

"Sora! Riku!" I called out.

Suddenly, I felt my heart tap into a strange dose of magic. Magic coming from pocket. Unaware at what was happening, I opened my eyes and slowly rose back on my feet.

"Huh?!" I gasped.

From where I stood, I spotted hundreds of Heartless who wanted my completely still. Almost as if they were frozen in time. I then turned around to check on the boys, only to find them to stopped.

"Sora? Riku?" I blinked in confusion.

"What happened?" I wondered.

My heart answered my own question by reacted to the object I had in my pocket. The green diamond I stored. I then glanced down at my pocket and realized what happened. The diamond must have casted Stopga in an attempt to protect me. As a way to show my gratitude, I smiled and placed my left hand over my heart.

"Thank you." I whispered.

With limited time left, I quickly disposed my keyblade grabbed the hedgehog. My plan was to carry him to safety and repeat what I've been trying to do since the Heartless arrived. Sadly, the plan backfired in a heartbeat as I witnessed time returning. The diamond's magic was wearing out, returning Sora's running speed back to normal. Sadly, he wasn't fast enough to save me.

"GAH!" I screamed.

"KAIRI!" My crush cried.

The tiny Heartless managed to trip me off my feet, flinging the unconscious hedgehog out of my hands and knocking down to the dark sand. Pain within my ankles began to hurt slightly, but that became the least of my worries. I quickly rolled over, only to find the tall merged Heartless reforming.

"Sora, stay back!" I heard Riku shout.

"But she needs our help!" Sora convinced.

"Listen to him, Sora! Or else they'll get you too!" I reasoned with him.

The Heartless then towered its formed long head, spinning around like a tiny tornado. Knowing what was going to happen, I summoned my keyblade again in hopes it would defend me. The Heartless rose its head back before diving at me. Before I knew it, I got showered into the dark abyss of our foe without my keyblade, cutting me from Sora, Riku, and the beach I was just laying on.

"Sor-...a." I spoke before drowning inside the belly of the beast.

Sora's POV

It happened so fast. One moment, she was with us trying to stop the Heartless with Riku and I. The next, she was gone. In one swing, she was swallowed by the Demon Tower, leaving nothing but her keyblade and our unconscious animal pal behind. Despite him lying in front of me, seeing the Princess of Heart's keyblade laying on the ground without its master was enough to sink my heart deeply.

"KAIRI!" Riku and I screamed in horror.

My biggest fear struck me once again. Once again, the promise I made to the young princess was broken. I thought our worries were over after we were reunited after I came back from Shibuya. Even after using the Power of Waking to save eher, the forces of darkness took her away from me again.

"Not again!" I said in a sad one.

Overwhelmed by the mixed emotions I had, I reached out ti Kairi's keyblade with my left hand and grabbed it. A keyblade that was round and curvaceous to the point of appearing harmless. One side of the hilt was formed in the shape of a breaking ocean wave, while the other is formed into a beige vine of sand that wraps around the shaft, which was colored to resemble a sunset. The vine was connected to a bouquet of colorful flowers, which formed the teeth of the Keyblade and entwined to outline a heart. A red silken keychain connected the hilt to a paopu fruit token, a recurring symbol of the bond between the princess and I.

"It's not over, Sora!" Riku spoke, grabbing my shoulder.

"We can still save her." He replied.

As I held two keyblades, I knew that my best friend was right. Our fight wasn't over. We still had to defeat the Demon Tower and there was still a chance to free Kairi. But little did we knew that we had more situations in our hands than before.

"Uhh, my head." A male voice moaned.

Riku and I rose our heads a little to find that our mysterious visitor was waking up. With little strength, he slowly got up on his feet and shook himself up to wake up some more.

"Woah!"

"Well, aren't you a looker!" The Hedgehog complimented our foe.

"Stay away from it!" Riku ordered.

"Huh?" The animal turned.

"Is that thing giving you two trouble?" He asked, giving us an odd look.

"You can say that." Riku answered.

"It just swallowed a dear friend of ours." I mentioned.

"Really?" The Hedgehog raised a green eye.

"Well then, just leave the rescuing to me." He smirked.

"Are you crazy?" I cried.

"Nope, just want to have some fun." The animal turned back to the Heartless.

As much as we wanted to stop him, the cocky hedgehog made his mind up. But what really surprised us was what he was capable of doing. In a blink of an eye, he ran around the enemy before dashing into it. Then, he rolled into a ball and began smashing into the tower repeatedly in rapid succession.

"HUUH?!"I muttered in disbelief.

"He's fast!" Riku reacted.

In fact, he was attacking so fast in every direction, the Demon Tower was shrinking in size. So small that it caused the Heatless to spit out Kairi.

"KAIRI!" I gasped.

The princess got flown near the shore, causing me to haul to her side. My heart began to speed up upon seeing her unconscious body, but another thing that caught my eye. The green diamond rolled out of Kairi's pocket, making the hedgehog also interested.

"The Chaos Emerald!" The hedgehog exclaimed.

"Chaos Emerald?" I blinked.

* * *

**Cliffhanger!**

* * *

**Please Review and Comment!**


	3. Chapter 3: Speedy Getaway

**Enjoy!**

* * *

"Chaos Emerald?" I blinked.

As puzzled as I was overwhelmed by the moment we were all in, I glanced down to the green diamond the blue hedgehog referred. The talking critter approached me and grabbed the mysterious gem, staring down at it too.

"What's a Chaos Emerald?" I asked.

"GAHH!"

A familiar voice cried out as I spotted Riku get knock back towards the hedgehog and I. The Keyblade Master was sent beside us, sliding towards the dark sea with his keyblade and scaring me in the process.

"Riku!" I cried.

"Are you okay?" The hedgehog called.

I then ran over to my best friend, discarded Kairi's keyblade from my left hand, and offered my assistance. Fortunately, Riku simply refused my help as he slowly stood backup with his weapon in his hand. Unfortunately, our foe seemed like it was about to repeat history. Like what it did to Kairi, the Demon Tower pointed its spinning long head at Riku and I, planning its next move on us.

"HA!"

Fortunately, the hedgehog had a plethora of surprises in store for us as he attacked the Demon Tower by surprise. Two rapid aerial spin dashes became enough to cut the shadowy monster down to size, defeating some that merged into it.

"I'd say it's a good time to leave this gloomy beach!" The blue animal suggested.

"Either said than done." I replied.

"Huh?" The hedgehog blinked.

"It's complicated, but we know a way out of here." Riku responded.

"Well, then get that girl and lead the way before…"

The blue hedgehog was then interrupted by the Demon Tower reforming behind him. Without Riku's orders, I went over to the unconscious princess and picked her up over my shoulders. Her weight was a little heavy to carry, but I didn't have a choice. As a Guardian of Light, it was my duty to protect those who possessed the pure light. Those who are pure hearted and Kairi was one of them.

"Hurry, Sora!" Riku called out.

"I got her!" I responded, running back to the Keyblade Master.

With the princess having a restful piggyback ride on me, it was time for the hard part. In order to return home, the Door to the Light needed to appear before us. The hard part was simply summoning the door since I already had my hands full with Kairi. Our escape was in Riku's hands as he pointed his keyblade towards the sun. A laser was then shot from the tip of his weapon and hit the sun, revealing the doorway to our freedom.

"The doorway's ope…"

Before I could even finish my call to the blue hedgehog, the Heartless took us by surprise. The swarm of Shadows quickly surrounded us, trapping us in a circle of darkness. Riku was able to defend himself, but the Princess of Heart's protection gave me a problem. It was difficult for me to use my keyblade while carrying Kairi, making me a sitting duck.

"Oh no!" I gasped.

"HANG ON!" The blue hedgehog cried.

In a flash, the blue critter plowed through some rows of Shadows until he stopped in front of us.

"Is that light show our exit?" The animal wondered.

"Well, yes, but…" I nodded, only to be interrupted.

"Grab my hand!" The hedgehog demanded.

He took my left hand and Riku's without any hesitation as I noticed the Shadows beginning to glow orange. They were about to charge at us and reform into their Demon Tower form. Fortunately, it seemed as if the hedgehog had a plan.

"Chaos Control!" The blue critter shouted.

Like what happened on Destiny Islands, a green light began illuminating brightly as I felt the "Chaos Emerald's" energy coming from the hedgehog's glove. The light engulfed us, shrouding our sights of the horde of Shadows; which was a sight to behold. Before we knew it, we were returned to the peaceful islands that Riku and I called home.

"Oof!"

We all landed back onto the calming beach, but Kairi's weight managed to knock me ono her. My back ended up lying on the young princess's stomach, causing my heart to rapidly accelerate in embarrassment as I quickly rolled around to check on her.

"We're back!" Riku exclaimed.

"It sure looks peaceful than wherever we were just at." The hedgehog observed.

"You don't even know the half of it." I replied.

"Huh?" The animal muttered.

"Sora, you stay here while I'll go and lock the door." The Keyblade Master ordered.

I gave my friend a serious nod; which gave him permission to do what needed to be done. One of us had to seal the Door to the Realm of Darkness or else the Heartless will traverse over to the peaceful islands. However, I felt as if Riku wanted me to look after Kairi and our new friend. He knew that the princess and I shared a special bond and he also figured I would explain everything to the blue hedgehog.

"Hey, thanks for saving us,...uh…" I paused.

"Sonic!" The critter spoke.

"Huh?" I muttered.

"I'm Sonic the Hedgehog!" He introduced himself.

"And it was no problem! I'm use to stuff like that." He accepted my thanks.

"Really?" I smirked.

"Although, I've never seen those creatures before." Sonic mentioned.

"You mean the heartless." I clarified.

"The Heartless?" The hedgehog repeated.

"Yeah, that's what they're called and that beach we were just on? That's their home realm." I briefly explained.

"Home realm?" Sonic blinked.

"The Realm of Darkness to be more precise." I replied.

* * *

_**Please Review and Comment!**_

* * *

**Next chapter will simply explain about the KH franchise and how Sonic came to the KH universe.**


End file.
